This volume is the result of a symposium entitled "Variation in Life Histories: Genetics and Evolutionary Processes" sponsored by the Program in Evolutionary Ecology and Behavior of the University of Iowa and held in Iowa City on October 13 and 14, 1980. Prompted by a recent upsurge of interest in the evolution of life histories, we chose this topic because of the obvious association between life history traits and Darwinian fit ness. If such an association were to be fruitfully investigated, it would require the closer cooperation of population and evolutionary ecologists and quantitative and population geneticists. To encourage such an association, our symposium had four major aims: first, to facilitate intellectual exchange across disciplines among an array of biologists studying life histories; second, to encourage exploration of genetic variance and covari ance for life history traits; third, to consider the ecological background for genetic vari ability; and finally, to facilitate a comparative overview both within and among species. Obviously such broad aims cannot be met totally in a single volume, but we think we have succeeded reasonably well in providing a representative and nourishing intel lectual feast. We see this book as a stimulus to the coordination of future efforts in an important and expanding area of inquiry. We have divided the book into six sections.

Life history theory seeks to explain the evolution of the major features of life cycles by analyzing the ecological factors that shape age-specific schedules of growth, reproduction, and survival and by investigating the trade-offs that constrain the evolution of these traits. Although life history theory has made enormous progress in explaining the diversity of life history strategies among species, it traditionally ignores the underlying proximate mechanisms. This novel book argues that many fundamental problems in life history evolution, including the nature of trade-offs, can only be fully resolved if we begin to integrate information on developmental, physiological, and genetic mechanisms into the classical life history framework. Each chapter is written by an established or up-and-coming leader in their respective field; they not only represent the state of the art but also offer fresh perspectives for future research. The text is divided into 7 sections that cover basic concepts (Part 1), the mechanisms that affect different parts of the life cycle (growth, development, and maturation; reproduction; and aging and somatic maintenance) (Parts 2-4), life history plasticity (Part 5), life history integration and trade-offs (Part 6), and concludes with a synthesis chapter written by a prominent leader in the field and an editorial postscript (Part 7).

There are many different types of organisms in the world: they differ in size, physiology, appearance, and life history. The challenge for evolutionary biology is to explain how such diversity arises. The Evolution of Life Histories does this by showing that natural selection is the principal underlying force molding life history variation. The book describes in particular the ways in which variation can be analyzed and predicted. It covers both the genetic and optimization approaches to life history analysis and gives an overview of the general framework of life history theory and the mathematical tools by which predictions can be made and tested. Factors affecting the age schedule of birth and death and the costs of reproduction are discussed. The Evolution of Life Histories concentrates on those theoretical developments that have been tested experimentally. It will interest both students and professionals in evolution, evolutionary ecology, mathematical and theoretical biology, and zoology and entomology.

This volume is the result of a symposium entitled "Variation in Life Histories: Genetics and Evolutionary Processes" sponsored by the Program in Evolutionary Ecology and Behavior of the University of Iowa and held in Iowa City on October 13 and 14, 1980. Prompted by a recent upsurge of interest in the evolution of life histories, we chose this topic because of the obvious association between life history traits and Darwinian fit ness. If such an association were to be fruitfully investigated, it would require the closer cooperation of population and evolutionary ecologists and quantitative and population geneticists. To encourage such an association, our symposium had four major aims: first, to facilitate intellectual exchange across disciplines among an array of biologists studying life histories; second, to encourage exploration of genetic variance and covari ance for life history traits; third, to consider the ecological background for genetic vari ability; and finally, to facilitate a comparative overview both within and among species. Obviously such broad aims cannot be met totally in a single volume, but we think we have succeeded reasonably well in providing a representative and nourishing intel lectual feast. We see this book as a stimulus to the coordination of future efforts in an important and expanding area of inquiry. We have divided the book into six sections.

There are many different types of organisms in the world: they differ in size, physiology, appearance, and life history. The challenge for evolutionary biology is to explain how such diversity arises. The Evolution of Life Histories does this by showing that natural selection is the principal underlying force molding life history variation. The book describes in particular the ways in which variation can be analyzed and predicted. It covers both the genetic and optimization approaches to life history analysis and gives an overview of the general framework of life history theory and the mathematical tools by which predictions can be made and tested. Factors affecting the age schedule of birth and death and the costs of reproduction are discussed. The Evolution of Life Histories concentrates on those theoretical developments that have been tested experimentally. It will interest both students and professionals in evolution, evolutionary ecology, mathematical and theoretical biology, and zoology and entomology.